Not a chance. (Famous last words! LOL!) Good observation though. The reason being is that when I put the battery connectors on the wires, I made sure to put the fuse link on the positive end (see picture above). And it's been working out for me for quite a number of years. Could I have made a mistake.....of course.....anyone can. But I'm very confident that I did not make that mistake; that's the first thing that I double check when hooking up the boat.
And that would not explain the unit working sometimes and sometimes not - and then just stopping altogether? Some good thoughts here - Thanks!